Do you remember the Power Balance Bracelet craze? Circa 2010, Shaquille O’Neal and other athletes were wearing silicone bracelets that had a “hologram” (a sticker) that was claimed to “resonate with the body’s natural energy field”, improving balance, strength, and flexibility. They were enormously popular until regulators and science caught up. Independent testing couldn’t find any meaningful performance benefits beyond placebo effects. The manufacturer subsequently faced lawsuits in the United States and filed for bankruptcy after agreeing to a settlement of approximately $57 million in 2011.
I was reminded of the Power Balance fad when I saw wellness patches on social media. I’ve previously blogged about “GLP-1 Patches,” but some products go well beyond weight loss. For example, the website for Restelle offers “Sleep” patches, “Weightless” patches, “NAD+” patches, “Energy” patches, “Focus” patches, and “Period” patches. Each patch is said to contain several different ingredients. For example, the “Sleep” patches are stated to contain magnesium glycinate 3mg, valerian root 5mg, hops 3mg, 5-HTP 1 mg, L-tryptophan 5 mg, and melatonin 5mg. The “Weightless” patches are said to contain Berberine extract 5mg, Fucoxanthin extract 3mg, Green tea extract 2mg, Pomegranate oil 2mg, Vitamin C 2mg, African mango seed extract 1mg, Vitamin B1 1mg, B2 1mg, B3 1mg, B5 1mg, and B6 0.5mg. Now I could do a deep dive on each of these ingredients in each patch, looking for direct evidence of efficacy when applied transdermally. But that would be a very long post. Instead, I’ll explain transdermal absorption and show the key challenges faced in transdermal drug delivery that illustrate why we should look at these efficacy claims for non-prescription wellness “patches” very skeptically.
Delivering drugs through the skin
Our skin is both a protective barrier and, under the right circumstances, a route for drug delivery. The outermost layer, the stratum corneum, consists of flattened, keratin-rich cells embedded in lipids and is remarkably effective at keeping water in and foreign substances out. That is a very good thing. Chemicals that do penetrate intact skin generally do so by passive diffusion, moving from an area of higher concentration on the skin surface to lower concentration in the tissues and blood beneath it. Small molecules, especially ones that have the right balance of water and lipid solubility, penetrate most readily. Conversely, large, highly water-soluble or charged molecules cannot cross the skin’s layers easily. And absorption is critical for drug delivery. It’s only after a substance passes through the stratum corneum, into the epidermis and dermis, that it can enter the capillaries and subsequently be delivered to the rest of the body.
Recognizing the potential to deliver drugs this way led to transdermal drug delivery research, with the intent of delivering medicine through intact skin. Although medicinal substances have been applied to skin for centuries, modern transdermal patches have arrived relatively late in the history of medicine. They really only reached widespread use in the late 20th century as advances in polymers, adhesives, and membrane technology made predictable delivery possible. Because that’s critical with transdermal drug delivery—you need predictable delivery in order to promise predictable, consistent effects. Patches can be very effective and useful as a means of getting drug through the skin. They can provide relatively steady drug concentrations over hours or even days. Importantly, delivery this way will bypass the gastrointestinal tract and the “first-pass” metabolism by the liver after gastrointestinal absorption, which can make oral use infeasible. The major limitation for transdermal drugs is that relatively few drugs have the physicochemical properties and potency needed to cross the skin in useful amounts.
The common transdermal patches that are licensed and sold today share some common characteristics. Nicotine is a small molecule, at about 162 Daltons (Da), and readily crosses biological membranes, making it suitable for patches that provide sustained nicotine exposure during smoking cessation. Nitroglycerin, about 227 Da, is small and lipophilic (fat-soluble) and is effective at very low systemic concentrations. Transdermal administration also avoids the extensive first-pass metabolism that follows oral administration (which is why we see sublingual tablets and sprays and not long-acting tablets). Estradiol is about 272 Da, and is a potent, lipophilic steroid hormone and therefore an excellent candidate for delivery through the skin. Fentanyl, an opioid narcotic, is about 336 Da, is larger but extremely potent and highly lipophilic, so only microgram quantities need to cross the skin each hour to produce an effect.
The existence and licensing of transdermal drug delivery patches isn’t evidence that this mechanism is a good mechanism to deliver drugs. Rather, the relatively few approved products illustrate the significant commercial and chemical barriers that exist to using this approach to drug delivery. It isn’t as simple as thinking “small molecule” = “good candidate for transdermal”. The ideal transdermal drug candidate is:
- small enough to cross the skin’s barrier
- lipophilic enough to pass through the skin, but not so lipophilic that it stays trapped in the skin’s outer layers
- potent enough so that a small amount of absorption can produce a systemic effect
How to test if patches work
Skin absorption can be studied both in the laboratory and in people. After laboratory testing with human or animal skin to prove feasibility, successful candidate drugs may move to human trials. Transdermal drug products are tested similarly to oral medicines, by measuring drug concentrations in the blood at multiple time points after the patch is applied. From the resulting concentration-time curve, researchers can then calculate standard pharmacokinetic measures including Cmax (the highest observed blood concentration) and AUC (area under the curve), which represents the body’s total systemic exposure to the drug over a defined period. They also measure Tmax, the time required to reach the maximum concentration. Unlike an immediate-release oral drug, which often produces a relatively sharp, quick peak followed by rapidly declining concentrations, a patch is generally designed to produce a slower rise and a flatter, more sustained delivery. After a patch is removed, concentrations may also decline relatively slowly because drug may remain in the skin’s outer layers and continue to enter the circulation.
Melatonin is an interesting candidate for transdermal delivery. It’s a hormone, about 232 Da, and is in the range of size for drugs that can be delivered transdermally. And there are small human studies that show that patches can produce measurable blood levels. However, absorption is slow and variable: peaks (Tmax) occur over 8-13 hours after application. There is evidence that melatonin accumulates in the skin and continues to enter the bloodstream for some time, even after the patch is removed. This makes a patch technically feasible for prolonged exposure, but not really suitable for supporting sleep. I was not able to find any studies that demonstrate reliable clinical effectiveness of melatonin administered in a patch. The challenges with manufacturing and dosing are likely the reason I couldn’t find any evidence that any health regulator has approved a melatonin transdermal patch.
Not every ingredient in a wellness patch is implausible for the same reason. The “Sleep Patch” I referenced above is said to contain magnesium glycinate, 5-HTP (about 220 Da), and L-tryptophan (about 204 Da), all of which are small enough that molecular weight alone does not rule out transdermal delivery. But molecular weight is only one factor. Magnesium presents a more fundamental problem: magnesium exists in the body as the charged Mg²⁺ ion, rather than as a small, neutral, lipid-soluble molecule that can readily diffuse through the stratum corneum. 5-HTP and L-tryptophan present a different challenge. Like other amino acids, they are predominantly zwitterionic at physiological pH, meaning they carry both positive and negative charges. That makes them highly polar and poorly suited to diffusing into the stratum corneum. So although their molecular weights are small, their chemical properties make substantial passive transdermal delivery through intact skin highly unlikely, without some means of enhancing penetration.
Vitamin C in the “Weightless” patch illustrates the same point. Ascorbic acid is tiny, about 176 Da, comparable in molecular size to drugs that can be delivered transdermally, yet it is water-soluble and readily ionized. Research on topical vitamin C has found that meaningful penetration depends strongly on factors such as concentration and pH; one study found (in a widely cited pig-skin study) that L-ascorbic acid had to be formulated below pH 3.5 to penetrate skin effectively. If you’ve seen vitamin C in cosmetics, you may notice that manufacturers are using specialized formulations and delivery technologies—and this is just to deliver it to the skin itself, not attempt systemic absorption. So the fact that the vitamin C molecule is small, at 176 Da, does not mean that putting it into an adhesive patch will produce meaningful systemic absorption. There are too many practical barriers to expect that there would be any absorption.
Finally, let’s look at examples where additional technologies are required for transdermal delivery. There’s published research into B12 that we can look at that is informative. Cyanocobalamin, the form typically found in supplements, weighs about 1,355 Da, several times larger than anything else we’ve discussed, and beyond what we can anticipate could be passively absorbed. Real, patented transdermal B12 delivery systems exist, and the patents themselves are explicit about what it takes: “physical methods” such as iontophoresis or stripping of the stratum corneum, or chemical penetration enhancers, because passive diffusion alone doesn’t move a molecule this size across intact skin. A 2026 study out of Aston University, published in the Journal of Pharmaceutical Sciences, delivered B12 across excised murine skin using dissolving microneedles, tiny needles that create temporary microchannels and then dissolve. So getting B12 into the bloodstream through the skin, but this molecule needs specific technology to deliver it. So if a wellness patch doesn’t have specific technology, it’s not likely able to surpass these barriers. Especially in a product combined with several other ingredients, each with its own physicochemical requirements.
Other ingredients in some of these patches aren’t even single compounds at all: valerian root, hops, berberine, green tea extract, pomegranate oil, African mango seed extract, etc. They aren’t single molecules at all. They’re whole plant extracts with no defined molecular weight—if we wanted to measure if it’s absorbed, we’d need to know what chemical to look for in the bloodstream.
Conclusion
Transdermal patches can be an effective drug delivery mechanism. Nicotine, fentanyl, estradiol, and nitroglycerin work as patches and as licensed pharmaceuticals because they share similar features: small, lipophilic, uncharged, and potent enough that a tiny absorbed dose still matters. When we look at the ingredients in wellness patches, you’ll find several red flags. Among the different ingredients that I reviewed, melatonin is the most plausible, but there is no published data that I could find that this works effectively to support sleep. Other ingredients, like magnesium, 5-HTP, L-tryptophan, and vitamin C, are small enough but are not expected to cross the skin because of their properties. B12 is too large and difficult to cross through the skin without product-specific enhancements like microneedles. And plant extracts aren’t single molecules with a defined size that would even allow someone to evaluate absorption. Leveraging real science to sell health and wellness products isn’t a new strategy. But in the case of wellness patches, there are so many scientific holes that it’s reasonable to ask if these products actually do anything at all. And in the absence of published evidence to show they are effective, that’s what the cautious consumer should conclude.